As a rule of thumb the averidge fuel drain is 40 litres, over the course of a week that’s a lot of wrong fuel.
To carry misfuel there is no special licences required as long as no more than 330 litres is carried in a vehicle, if you carry more than that an ADR licence is needed
Storing mixed fuel is regulated by the environment agency, it must be kept safe, secure and have protection against leaks from ruptured storage tanks, (double and triple bunding)
There are a number of uses for mixed fuel, I have listed some of the more common ones:
1) Use in space heaters for a large garage as done by an un-named gentelmen in the west country (I suspect it will not end well)
2) mixing with bio-diesel to “thin” it up – only done in small quantity
3) re refining, this is done by 2 oil refineries in the uk who take 28.000 litre tanker loads, the process is simply to put it through the oil refinery again and split it back into a diesel and petrol, duty does not need paid on this but then problem is getting rid of it after it is refined because most petrol stations are tied in to exclusive supply contracts with the major oil companies
4) use in specialist military vehicles: rolls royce made an engine for tanks that can run on petrol or diesel, or a mix of both. It’s noise smelly and very loud, there are offroad ‘drive a tank for a day’ type sites that buy it
5) Cleaning engine parts, mixed fuel has good cleaning properties that work well with oils, it is used by garages and mechanics to clean brakes and engine parts
6) Burning stuff, mixed fuel sometimes brings out the inner pyro, and some people just can’t pass up the opportunity to torch a bit of wasteland
The AA get their fuel recycled back into petrol and diesel and the going rate is between 30 and 40p per litre for contaminated fuel, but with everything volume is the key. Handling mixed fuel in low quantities is expensive, and many garages go out of their way to not have to touch the stuff.
With diesel now at £1.40 per litre I expect the recycling will take a boost